This invention relates to a fuel injection control system and more particularly to an improved system for controlling a fuel injector to preclude against deleterious effects if fuel remains in the injector after the engine is shut off.
The use of fuel injection as a charge former for internal combustion engines is well known. It is also well known that fuel injection and particularly direct cylinder injection is particularly useful in two cycle engines in controlling their exhaust emissions and fuel economy. Although fuel injection systems have a wide variety of advantages, there are some problems, particularly with certain types of fuel injectors.
For example, one type of fuel injector includes a chamber into which fuel is injected. This chamber is then communicated with the engine through an injector valve that is opened and closed to control the injection directly to the engine. Oftentimes, air may also be charged into the chamber, either along with the fuel or at the same time the fuel is introduced. Although this type of injector is highly advantageous, when the engine is shut off, there tends to remain some residual fuel in the chamber and in the area between the injector valve and its seat. Since the engine will still be at an elevated temperature, this fuel may carbonize and cause problems on subsequent operation of the injector.
It is, therefore, a principal object of this invention to provide an improved fuel injector.
It is a further object of this invention to provide an improved fuel injector wherein residual fuel will not be retained in the injector when the engine is stopped.
With injectors of the type utilizing both air and fuel, the air pressure may also be existent in the chamber after the engine has been stopped. This can give rise to some problems in that an attempt to service the injector will cause this pressurized air to escape rapidly and may cause some damage.
It is, therefore, a further object of this invention to provide an improved air fuel injector wherein air is purged out of the chamber when the engine is shut down.